Conversion process and apparatus therefor



Feb. 12, 1946. H. z. MARTIN ErAL 2,394,928

CONVERSION PROCESSES AND APPARATUS. TI-EREFOR,

.Filed Feb. 27, 1941 2l 'sheets-sheet 1 CYC N :PA T072 CYcLoNs.SLPAtA-rma 59 f5 Il 5/ N f 52 f A MIB oNTR-QL ,y JEPAZATGR. A

Feb. l2, 1946. H. z. MARTIN ETAI. f 2,394,928

I' y CONVERSION PROCESSES AND APPARATUS THEREFOR.l I

Filedrebyzv, 1941 2 sheets-sheet 2 Patented Feb. 12, 1946 oo NvEnsIoNPaocnss AND mAnA'rU 'rnsaaroa Homer Z. Martin, Elizabeth, and Eger V.Murphree and Edwin J. Gohr, Summit, and John M. Graham, Dunellen, N. J.,assignors to Standard Oil Development Company, a corporation of Delawarei' vAnnlcamm February 27, 1941, serial No. 380,888 v (c1. 19e-52) f 12Claims.

This invention relates to conversion processes wherein gases or vaporsare treated with finelydivided material and pertains more particularlyto processes wherein the finely-divided material is successivelyinjected or intermixed with different types of gaseszwhich should not beintermingled.

In certain industrial processes wherein powdered materialislsuccessively contacted with difi'rent gaseous agents, it is of utmostimportance to prevent the intermingling of such gases. One specificexample of such an operation is the catalytic cracking of hydrocarbonoils wherein the catalyst innely-divided form is injected into thestream of oil vapors to be cracked, the catalyst subsequently separatedfrom the cracked products, and reinjected into a stream of oxidizing gassuch as air for removing carbonaceous deposits from the catalyst mass.In such operation safety requires that the air or other oxidizing gas beprevented from intermingling with the oil vapors to-be cracked in ca'seabnormal operating conditions should arise.

The object of the present invention is toprovide a method and apparatusfor preventing the intermixing of the two gases.

The specific object of theinventon is to provide an improved method andapparatusfor preventing intermingling of regenerating gas and oil vaporsin catalytic cracking operations wherein a powdered cracking catalyst isemployed.

Other objects and advantages of the invention will be apparent from thedetailed description hereinafter, in -which reference will be made tothe accompanying drawings.

In the drawings, Fig. 1 is a diagrammatic view of a catalytic crackingapparatus to which the invention may be applied; and

Fig. 2 is an enlarged detailed View partly diagrammatic of certain`safety controls forming part of the present invention.

Referring to Fig. l, the reference character I designates a charge linethrough which the oil to be treated is introduced into the system. Thisoil may comprise a clean condensate stock such as a gas oil or it may bea residual stock containing unvaporizable constituents under theconditions .obtained within the cracking zone. 'I'he charging stock fromline I0 is forced by means of pump II through a vaporizing coil I2located in a. heating furnacewherein the oil is heated to a temperaturesufficient to" effect substantial vaporization of the oil. The heatedoil from the vaporizing coil I2 is transferred through line I3 to aseparator Il wherein vapors separate from unvaporized residue. Theunvaporized residue is withdrawn from the separator through line I5 andmay be subjected to any further treatment desired outside of the purviewof the present invention. i

Vapors liberated in separator Il pass overhead through lines I6 and l1to a superheating coil I8 wherein the vapors may be further heatedbefore passing to the cracking zone.

In cases where a clean condensate stock which.

is completely vaporizable is employed, the separator I4 may be omittedor the oil vapors from the initial coil y I2 may by-pass through line I9directly to the heating coil I8. Products from heating coil I8 may passthrough line 2l to ay dispersion chamber or chest 22 wherein they areintermixed with -a powdered catalyst introduced through conduit 23. Thiscatalyst may be any suitable cracking catalyst capable of effecting or.acceleratingthe cracking of oils.

The combined mixture of catalyst and oil vapors is transferred throughline 25 to a reaction chamber 28 wherein the oilv vapors are retainedfor a period sufficient to obtain the desired amount of cracking. Thevelocity of the oil vapors passing through reaction chamber 26 ispreferably insuillcient to carry the catalyst along at substantially thesame velocity as the vapors. In other words, the velocity is such thatthe catalyst tends to separate out of the oil stream during its passagethrough the reaction chamber. By operating at this relatively lowvelocity, there is continuous churning or intermixingv of the powderedcatalyst within the reaction chamber and uniform conditions aremaintained. As an example, the time of residence of the oil vaporswithin the' cracking zone may be of the order of from 5 to 50 secondsmore or less, whereas the resident time of catalyst within the reac tionzone may be of the order of 2 minutes to an houror more. The velocity ofthe oil vapors is preferably sufficiently high, however, to preventcatalyst from completely settling and packing within the reactionchamber. As a result, the oil vapors leaving the reaction chamber can beused as a carrier for removing the catalyst therefrom.

The cracked products containing catalyst entrained t erein leave thereaction chamber 28 through lne 2l and pass to a cyclone separator 28 orsome equivalent device for separating finelydivided solids from gases.The oil vapors sepa rated from the catalyst in the separator 28 arepassed overhead through line 29 and may be passed to any suitablerecovery .system for segregating the desired motor fuel product. Ifdesired, the overhead products from the first separator 28 may be passedto a further separating and purifying apparatus, such as additionalcyclone separators, for further removal of residual powdered materialfrom the oil vapors before passing to the fractionating tower or otherrecovery apparatus.

Catalyst separated in the initial separator 28 is removed from thebottom therefrom through conduit 3| and is discharged into a stream ofinert gas, such as steam introduced through line 32 which may serve toremove volatile hydrocarbons from'the catalyst mass. The mixture ofinert gasand catalyst passes through line 32 to a second cycloneseparator 33, wherein the catalyst is separated from the inert gas. -Thestripping gas is rejected from the second separator through line Y 34and the catalyst separated is collected in the subject the catalyst to aregenerative treatment to remove carbonaceous deposits before returning'the same to the cracking zone. To this end the catalyst from the bottomsection of the cyclone separator 33 discharges through a verticalconduit or standpipe 35 into a stream of air or other oxidizing gasintroduced through line 36. The height of the standpipe or column 35 ispreferably such as to develop a pressure at the bottoni thereofsuillcient to feed the catalyst into the stream of oxidizing gas whichin turn must be under a pressure at least suillcient to overcome theresistance of the regenerating circuit to the flow of such a mixture ofgas and powdered material. In order to transmit the static pressurethrough the length of the column or standpipe 35, catalyst containedtherein must be maintained in a freely flowing condition or in ailuidized state. In many instances it is necessary to introduce afluidizing gas at one or more spaced points along the length of thecolumn through lines 31. 38 and 33 in order to maintain the catalyst ine, freely owing state.

'I'he bottom portion of the column 35 is provided with a pair of valves4I and 42, one of which may be controlled to regulate the amountl ofcatalyst owing into the stream of regenerating gas and the other ofwhich may be operated automatically to close in case abnormalconditionsshould arise within the operating unit which would tend tocause a ilowV of the regenerating gas upwardly through the column 35 andinto the stream of cracked vapors removed from cyclone Separator 33.

Referring to Fig. 2, either or both valves 4l and 42 may be operated bya level controller in the hopper located above the standpipe 35 toautomatically close when the level in the hopper drops below apredetermined point which might permit air to pass upwardly through thestandpipe into the hopper. Any suitable level controller may belemployed for regulating thel valves. In Fig. 2 the level controller isshown in the form of two tubes 43 and 44 connected to the hopper atspaced points through which an inert gas is supplied through line 45under a pressure sufiicient to feed the gas into the hopper. A Ustube 48illled with mercury or other suitable conductor may be provided; havingone end connected to the tube 43 and the opposite end connectedthroughylie 4l with tube 44. 'I'he difference iny level of the mercuryand the two legs of the U-tube indicates the difference in pressurebetween the two tubes 43 and 44. Consequently, if the level in thehopper should drop below the lower tube 44, the outlet pressure of thetwo tubes 43 and 44 would be substantially the same and consequently thelevel of mercury on both legs of the U-tube 45 would be substantiallyequal. By providing electrical contact points at the bottom of theU-tube such as at 48 and at an intermediate point 49 in the U-tube 46when the mercury in both legs of the U-tubes tends to become equal, anelectrical circuit may be lclosed operating suitable relay switches orother 'equivalent devices in a control box 5| which in turn may causeeither one or both of the valves 4i and 42 to close.l As illustrated, asteam line 52 is provided between the two valves. Upon closing of thevalves 4i and 42, valve 53 in steam line 52 may be opened automaticallyby suitable relay switches in the control box 5I to introduce steambetween the two valves under a pressure in excess of that existing inthe oil line or in the standpipe. Consequently, if either of the twovalves should leak, the steam or other inert gas introduced through line52 would now outwardly against the oil vapors and thus prevent th'eirpassage to the standpipe 35.

As a further precaution, a second U-tube 54 containing mercury or otherpressure diiferentials, controller may be interposed between th'e airline 38 and the standpipe 35 immediately above valve 4I so that if thepressure in the air line should approach the pressure above the valve 4ian electrical -circuit may be closed by suitable contact points 55 and58 which in turn may operate suitable relay switches for the closing ofvalves 4| or 42, or both. Wh'en this happens, valve 53 in steam line 52may also open automatically to introduce steam between the valves.

As a further precaution, the level controller 45 orthe pressuredifferential controller 54 may be employed to automatically operatesuitable valves in the oil lvapor lines to cut oil the supply of oilvapors to the system and to by-pass them to suitable recovery equipment(not shown).

While the level controller and the pressure differential controllershave been shown in the form of vU-tubes containing mercury, it will be'understood that any other suitable controller operating in a similarmanner can be employed in their stead. Furthermore, while two separatevalves have been shown, one of which is adapted to remain openy duringnormal operations and to close automatically in case of abnormaloperations,- as hereinbefore described, whereas the other is adapted tobe operated to regulate the flow of catalyst into the air line 35, itwill be understood that a single valve may be provided to operate bothas a control and asa shut-off valve. if desired. However, as a matter ofsafety, it is preferred to provide a separate shut-olf valve operatiindependently in case of abnormal con-y ditions l:flising within theunit which might tend to cause the intermingling of the air with the oilvapors. v

Returning again to Fig. l, the catalyst recovered from .the crackedproducts and collected in standpipe 36 is fed at a controlled ratethrough catalyst undergoing regeneration at a velocity approaching thatof the air. In other words, the velocity of the stream is regulated inproportion to the size and density of th'e catalyst particles so thatthe particles move through the regenerating zone at a much slower ratethan the air stream. Consequently, there is continuous intermingling ofthe catalyst particles with the air stream resulting in the maintenanceof a uniform temperature within the regenerator. This is of particularimportance since in many cases the activity of the catalyst is seriouslyimpaired if the temperature is allowed to exceed a predeterminedmaximum. For example, when regenerating activated clays, the temperaturein general should be maintained below 1200 F. On the other hand, toeffect rapid regeneration of the catalyst, it is desirable to carry. outth'e regeneration at, the maximum temperature which will not impair theactivity ofthe catalyst. By regulating the flow of terial before beingvented or exh'austed to theatmosphere. Regenerated catalyst separated inthe cyclone separator 60 collects in hopper section 62 locatedimmediately below from which it passes into eithrr or both of twostandpipes 63 and 64. Catalyst collected in standpipe 63 discharges intothe dispersion zone or chamber 22 through which the oil vapors pass fromline 2|.

The bottom of the standpipe 63 is also provided with two valves 65 and66, one of which is adapted to be controlled to regulate the flow ofcatalyst into the oil vapors and the other of which' is adapted tofunction as a shut-oil valve in case' abnormal operating conditions tendto arise which might cause transfer of oil vapors upwardly .through thestandpipev 63. 'I'he shut-oil.' valve and th'e control valves 65 and 66may be operated in the same manner as valves 4i and 42 located in thestandpipe 36. In view of this, corresponding parts of the controlmechanism have been shown in the drawings by prime numbers. The shut-oilvalve which it be assumed to be valve 66 may be operated automaticallywhen th'e level of the hopper 62 drops below a certain point or when thepressure of the oil vapors in the dispersion chamber 22 tends to exceedorapproach the pressure on the opposite side of valve 66. t

In order to control the temperature within the regenerator 68, a portionof the regenerated catalyst may be recirculated after having been cooledto the desired point. To this end the portion of the catalyst collectedin the standpipe 64 is passed through valve 61 into a gas stream passingk through line 68. The gas stream passing through mal operation. Suchabnormal pressure condi- What is desired to be line 63 may be air or itmay be an inert gas serving as a carrier for the catalyst. The stream ofregenerated catalyst and gas carrier passes through line 68 .through acooler 69 and then passes through line 10 into the regenerator 53 whereit intermixes with the unregenerated catalyst introduced through line 36and serves asv a cooling agent therefor. In order to more closelyregulate the catalyst within the chamber 58, a portion of theregenerated Vcatalyst recycled through' line 68 may by-pass around thecooler 69 through line 1 I In order to maintain the catalyst in thestandpipe or vertical column 63 and 64 in a suitable freely flowingfiuidized state, the fiuldizing gas may be introduced at one or morespaced points through lines 12, 13, 14, 16 and 16.

The safety controls hereinbefore described are for the purpose ofpreventing intermingling of oil vapors and regenerating gas eitherbybacking up of regenerating gas upwardly through standpipe' 35 or bybacking up of oil vapors through standpipe 63'.

Conditions may also arise which might tend to force oil vaporsdownwardly through standpipe 35 intothe air stream in line 36 orregenerating gas downwardly through standpipe 63 to the oil vapor streamin mixing Jet 22.

To avoid these possibilities the transfer line 21 may be. provided withan automatic pressure control valve adapted to cut off the oil supply orto by-pass the oil to suitable run-down and recovery apparatus notshown. Such pressure controller may also function to close either orboth@ of valves 4i and 42 and to open stream line 62.

Likewise,a pressure controller 8| may be placed in line 53 leading fromregenerator 58. 'Ihis controller may function to cut the air supply inline 36 and line 66 and may also function to close either or bothvvalves 65 and 66 and to lopen a stream line therebetween. l

While the invention has been described as applied to a particular typeof catalytic cracking apparatus, it will be understood that theinvention is directed to a method and apparatus for preventingintermixingof oil vapors and regenerating gas and may be applied toformsv of apparatus other than that shown.

The term abnormal pressure conditions. as herein employed means pressureconditions materially different than those existing during nortions mayarise," for example, by building up of excessive pressures on the oilvapors due to coking or plugging of oil lines or from other causes,

or a failure in pressure on the regenerating gasp,

or vice versa.

Having described the preferred embodiment of the invention, it will beunderstood that it embraces such other -variations and modifications ascome within the spirit and scope thereof.

protected by Letters Patent is :l

1. In a process-for contacting solids and gases wherein one stream. ofreactants passes through a reactionX chamber containing a relativelydense mass of finely-divided contact material, a second stream of gasespasses through a second chamber containing a mass of said iinely-dividedcontact material, the contact material from one chamber beingcontinuously passed to the other through a valved conduit in opencommunication with said chambers and wherein it is desired to preventintermingling of gases from one chamber with the gases from the other;the improvement which comprises imposing a pressure on the contactmaterial passing .through said'F conduit substantially greater than thepressureial on the gases passing to the chamber into which said contactmaterial passes under normal operating pressure conditions, measuringthe difference between the pressure on the contact ms.-z

terial in said conduit and the pressure existing in said last-namedchamber under normal conditions and closing the valve in response to apassed through a conversion chamber containing a relatively dense massof finely-divided contact material, a regenerating gas is simultaneouslypassed through a second chamber containing a mass of said iinely-dividedcontact material, the

- contact material from the conversion chamber being continuouslytransferred to the regenerating chamber through a valved conduit in opencommunication with said chambers; thie improvement which comprisesimposing a pressure on the finely-divided contact material passingthrough said conduit substantially greater than the pressure on thegases passing through the rcgenerating chamber, measuring the differencebetween the pressure on the contact material in said conduit and thepressure on the regenerating gases passing through said regeneratingchamber and closing the valve in response to a predetermined reductionin said pressure differential to prevent intermingling of theregenerating gas with the oil vapors.

3. In a process defined by claim 1, the further improvement whichcomprises injecting an inert gas into said conduit when said pressuredifference drops below a predetermined value.

4. In the process dened by claim 2, the further improvement whichcomprisesdiscontinung the `supply of oil into said conversion chamberwhen the pressure difference drops below a predetermined value.

5. In .an apparatus comprising a reaction chamber adapted to contain amass of finelydivided Acontact material, means for passing a stream ofgases tobe reacted through said reaction chamber in direct contact withsaid iinelydivided material, a second chamber. means for passing asecond stream of gases through. said last-named chamber, a conduithaving one end in open communication with said iirst-named stream ofgases and the opposite end in open com munication with said last-namedstream of gases,

terial is transferred. and means responsive to a predetermined change'in the differential between the pressure imposed on the contact materialpassing through the conduit and the pressure on said last-named gasstream to close said conduit.

6. In an apparatus for carrying out chemical reactions in the presenceof finely-divided contact material comprising a reaction chamber adaptedto contain a mass of said finely-divided contact material, means forpassing a stream of gases through said reaction chamber inl directcontact with said finely-divided material, a regeneration chamber forregenerating said contact material, means for passing a stream ofregenerating gas through said regenerating chamber, a conduit having oneend in open communication with said stream oi' reaction gases and theopposite end in open communication with said stream ot regenerationgases. said conduit being adapted to transfer finely-dividedcontactmaterial from one of said gas streams to the other, means forimposing a pressure on, the contact material passing through saidconduit substantially greater than the pressure on the stream of 5 gasesinto which said contact material is transferred, and means responsive toa predetermined change in the differential between the pressure imposedon the contact material passing through said conduit and the pressure onsaid last-named stream of gases to close said conduit.

'1. In an apparatus for carrying out the conversion'oi hydrocarbon oilsin the Presence of a iinely-divided conversion catalyst which requiresfrequent regenerationscomprising a conversion chamber, means for passinga stream of hydrocarbon vapors to be reacted through said conversionchamber, means for introducing nelydivided conversion catalyst into saidstream of hydrocarbon vapors, a regeneration chamber, means for passinga stream of regeneration gases through said regeneration chamber, aconduit having one end in open communication with the hydrocarbon vaporsand the opposite end in open communication with said stream ofhydrocarbon gases, said conduit being adapted vto transferilnely-divided conversion catalyst from one of said streams of gases tothe other, means for imposing a pressure on the finely-dividedconversion catalyst passing through said conduit substantially greaterthan the pressure on the stream of gases into which said conversioncatalyst is transferred, and means responsive to a predetermined changein the diierential between the pressure imposed on the conversioncatalyst passing through said conduit and the pressure on the last-namedgas stream to close said conduit.

8. In the apparatus defined by claim 7. the further improvement whichcomprises means responsive to said pressure differential for injectingan inert gas into said conduit.

9. In the apparatus defined by claim 7, the further improvement whichcomprises means responsive to said pressure differential fordiscontinuingthe flow of hydrocarbon vapors.

10. In the apparatus defined by claim 7, the

. further improvement which comprises means resaid conduit being adaptedfor transferring nelydivided contact material from one or said streamsof gases to the other, means for imposing a pressure on the contactmaterial passing through said conduit substantially greater than thepressure on the stream of gases into which said contact ma- .75

sponsive to said pressure differential for stopping the flow of saidregeneration gas. 4

11. In an apparatus comprising a reaction chamber, means for passing aconned stream of reaction gases through said reaction chamber, means forintroducing finely-divided contact material into said stream oi' gases,a regeneration chamber for said contact material, means for passing aconiined stream of regeneration gases asa-acca y ceous deposits fromsaid contact material through said regeneration chamber, a verticalconduit havthrough said regeneration chamber, a vertically disposedconduit having one end in openv communication with said stream oi'reaction gases land the opposite end in open communication with saidstream of regeneration gases, means for transferring finely-dividedcontact material from one of said gas streams into the upper end of saidconduit, means for discharging the contact material at the bottom ofsaid conduit into said other stream, means for controlling the rate ofdischarge of said contact material into said lastnamed stream, saidlast-named means being normally controlled to maintain a predeterminedlevel of ilnely-divided contact material within said conduit, meansadapted to maintain a iluidizing gas in admixture with saidfinely-divided material within said conduit to keep said contactmaterial in a freely flowing, iluidized state to develop thereby ahydrostatic pressure at the base thereof, the level of said contactmaterial within said conduit being normally controlledto develop ahydrostatic pressure` at the base of said conduit substantially greaterthan the pressure on the gas stream in open communication therewith, andmeans responsive to a predetermined reduction of said level to closesaid' conduit.

12. An apparatus for the conversion of hydro-v carbon oils wherein theoils are converted in the presence of a finely-divided conversioncatalyst .comprising a conversion chamber, means for pass- ,ing aconfined stream of hydrocarbon vapors to chamber, means for passing aconnned` stream of regeneration gases capable of burning carbonaterialfrom the bottom of said conduit into the other stream of gases,- meansfor controlling the rate of discharge of said contact material into saidlast-named stream, said control means being normally regulated tomaintain a predetermined level y of nely-divided material within saidconduit, means adapted to maintain a uidizing gas in admixture with saidfinely-divided material within said conduit to keep said contactmaterial in a freely ilowing, fluidized state and thereby develop ahydrostatic pressure at the base thereof, the

level of said contact material within said conduit being normallycontrolled to develop a hydrostatic pressure at the base of said conduitsubstantially greater than the pressure on the gas stream into whichsaid contact material discharges, means responsive to a predeterminedchange inthe difterential'between thepressure on` the contact materialat the baselof said conduit and the pressure `on the gases into whichsaid contact material discharges to close said conduit,

and further means responsive to a predeterminedl reduction in the levelof said contact material in said conduit to close said conduit.

HOMER. Z. MARTIN. EGER V. MURPHREE. EDWIN J,- GOHR.

JOHN M. GRAHAM.

